BALANCED OCCLUSION

[Audio] BALANCED OCCLUSION. BALANCED OCCLUSION.

[Audio] DEFINITION: The tooth contact pattern (dynamic occlusion) where teeth are in contact on both the mediotrusive and laterotrusive sides when moving sideways from and towards maximal intercuspal position; the contact pattern is considered desirable for complete removable prostheses, because functional movements may then have the capacity to discourage dislodge ment of the prosthesis and improve oral comfort; (GPT-10) A three point contact (usually one anterior and two poterior) at centric relation is not sufficient for balanced occlusion instead there should be simultaneous contact of all teeth. Balanced occlusion is absent in natural dentition..

[Audio] Types of complete denture occlusion Complete denture occlusion can be of various types namely; Balanced occlusion Monoplane occlusion Lingualized occlusion Neutocentric occlusion Each types of occlusion has its specific indication, contraindication, advantages and disadvantages. Most common type used in denture is balanced occlusion..

[Audio] Characterstics of balanced occlusion All the teeth of the working side (central incisor to second molar )should glide evenly against the opposing teeth. No single tooth should produce any interferences or disocclusion of the other teeth. There should be contacts in the balancing side, but they should not interfere with smooth gliding movement of the working side. There should be simultaneous contact during protrusion..

[Audio] Is “Balance” Necessary? “Bolus in” “Balance out”.

[Audio] Sheppard stated that ,”enter bolus, exit balance” according to this statement , the balancing contact is absent when food enters the oral cavity. this makes us think that balanced occlusion has no function during mastication; hence it is not essential in complete denture but this statement is not true. Brewer reported that on an average, a normal individual makes masticatory tooth contact only for 10 minutes in one full day compared to 4 hours of total tooth contact during other functions. so for these 4 hours balanced occlusion is more necessary to maintain denture stability hence this is more critical in para-functional movements..

[Audio] General considerations for balanced occlusion ideal balanced occlusion can be achieved in cases with wide and large ridges and in complete dentures, with teeth arranged close to the ridge. Teeth arrangement away from the ridge and those that rest on narrow ridge have poor denture stability. Ideal balance can be achieved by arranging the teeth slightly lingual side of the crest of the ridge. Teeth arranged buccally will lead to poor balance occlusion. Forces of occlusion should centered antero-posteriorly in the denture..

[Audio] Types of balanced occlusion Unilateral balanced occlusion Bilateral balanced occlusion Protrusive balanced occlusion Lateral balanced occlusion.

[Audio] Unilateral balanced occlusion This is a type of occlusion seen on occlusal surfaces teeth on one side when they occlude simultaneously with a smooth uninterrupted glide. this is not followed during complete denture construction. It is more pertained to fixed partial denture..

[Audio] Bilateral balanced occlusion This is a type of occlusion that is seen when simultaneous contact occur on both sides in centric and eccentric positions. For minimal occlusal balance there should be at least three points of contact on occlusal plane. more the numbers of contact, better the balance..

[Audio] Bilateral Balanced Denture Occlusion Protrusive Balancing Side Working Side.

[Audio] Protrusive balanced occlusion This type of balanced occlusion is present when the mandible moves in forward direction and the occlusal contacts are smooth and simultaneously anteriorly and posteriorly. There should be at least three points of contact in the occlusal plane.two of these located in posteriorly and one should be located in anterior region. This type of occlusion is absent in natural dentition..

[Audio] Factors that govern the protrusive balance Inclination of condylar path Angle of incisal guidance Angle of plane of occlusion Compensating curve chosen for orientation with the condylar path and incisal guidance. Cuspal height and inclination of the posterior teeth..

[Audio] protrusive balance. protrusive balance. [image].

[Audio] Lateral balanced occlusion In lateral balance, there will be minimum simulataneous three point contact( one anterior and two posterior) present during lateral movement of mandible. It is absent in natural dentition. When a dentulous person with canine guided occusion moves his mandible to right, only the canine will be the tooth that contacts the opposing teeth. and even the canine of opposing side will not have the contact. If canine guide occlusion is followed in complete denture then it will lose its stability due to lever action..

[Audio] Factors that govern the lateral balance The inclination of the condylar path on the balancing side. The inclination of the incisal guidance & cuspid lift. The inclination of the plane of occlusion on the balancing side & working side. .The compensating curve on the balancing side & working side. The buccal cusp heights or inclination of the teeth on the balancing side. The lingual cusp heights or inclination on the working side. The Bennett side shift on the working side..

[Audio] LATERAL BALANCE Working side balance Balancing side balance.

[Audio] Concepts proposed to attain the balanced occlusion Many authors proposed different concepts for obtaining balanced occlusion. Gysi’s concept ; He proposed the first concept towards balance occlusion in 1914.he suggested arranging 33 degree teeth could be used under various movement of the articulator to enhance the stability..

[Audio] French concept(1954) he proposed lowering the occlusal plane to increase the stability of the denture along with balance occlusion. Sears concept he proposed balance occlusion for non anatomic teeth using posterior balancing ramps or an occlusal plane which curve anteroposteriorly and laterally.

[Audio] Pleasure concept he introduced a pleasure curve or posterior reverse lateral curve to align and arrange the posterior teeth in order to increase the stability of denture. Frush concept he advised arranging teeth in one dimensional contact relationship, which should be reshaped during try in to obtain balanced occlusion..

[Audio] Hanau ‘s quint Rudolph.E.hanau purposed the nine factors that governs the articulation of artificial teeth. Horizontal condylar inclination Compensating curve Plane of orientation Buccolingual inclination of tooth axis Protrusive incisal guidance Sagittal condylar pathway Sagittal incisal guidance Tooth alignment Relative cusp height.

[Audio] He mathematically charted the nine factors and listed the laws of balanced occlusion. Then he combined original factors and reduced them to five. He showed how they affected each another with a lever diagram called as “ Articulation Quint ”.

[Audio] Hanau’s Quint Five Factors Affecting Occlusal Balance Condylar Inclination Incisal Guidance Occlusal Plane Inclination Compensating Curve Cuspal Inclination.

[Audio] Thielesmann: Subsequently simplified Hanau’s factors in a formula for balanced occlusion. B.O.= K x I Op x C x OK Where K - condyle guidance I- Incisal guidance C - Cusp height & inclination. OP - Inclination of occlusal plane. OK - Curvature of occlusal surface..

[Audio] BO= Condylar Inclination OccPlane x Incisal Guidance x Cuspal Inclination x CompCurve.

[Audio] Clinical application 1 steep cusps produce more denture base shifting 2. forces of occlusion should be balanced from right to left and anterior to posterior 3. steep incisal guide angle in complete dentures makes attaining balance more difficult because it requires steeper cusps, and/or an increase in compensating curve and/or an increased occlusal plane angle, all of which compromises the stability of the denture base 4. if phonetics and/or esthetics require a significant vertical overlap of the anterior teeth, then a compensating horizontal overlap is necessary to keep the incisal guidance from getting too steep..

[Audio] Trapozzanos concept of occlusion he reviewed the hanau quint and proposed his triad of occlusion.according to him only three factors are necessary for balanced occlusion. He dismissed the plane of occlusion and compensating curves..

[Audio] Boucher’s concept Boucher disagreed with Trapazzano & felt that there was a need for compensating curve & that the occlusal plane should be included only in its correct anatomic position………………………..

[Audio] Lotts concept he clarified the hanau laws of occlusion by relating them to posterior disocclusion. The greater the angle of the condylar path greater is the posterior separation during protrusion. The greater is the angle of overbite greater is the separation in the anterior and posterior regions irrespective of the angle of condylar path. The greater the separation of posterior teeth the greater or higher must be the compensating curve. Posterior separation beyond the balancing ability of the compensating curve can be balanced by the introduction of plane of orientation. Greater the separation of posterior teeth greater must be the height of cusps of posterior teeth.

[Audio] Bernard Levin:In 1978, described the laws of articulation in a “ Quad”. He feels that four guiding factors are important to achieving protrusive & lateral balance. As each guiding factor is increased, the amount of posterior separation is proportionally increased.

[Audio] Factors influencing balanced occlusion The five principles factors in the laws of occlusion as stated by Hanau are: Inclination of condylar guidance. Prominence of the compensation curves. Inclination of the plane of orientation. Inclination of the incisal guidance. Height of the cusps.

[Audio] 1.CONDYLAR GUIDANCE: It is the mandibular guidance generated by the condyles traversing the contours of the glenoid fossa. It is the posterior end-controlling factor. It is independent of tooth contact. The condylar path is determined on the patients by a protrusive record & set on the instrument. Kurth claims that the condylar path is not same for varying incisal guidance. Payne says that the mandible can move to follow steep cusps, modified cusps & teeth with no cusps when there is posterior occlusal harmony & no anterior incisal interference. Weinberg has demonstrated that the condylar path may vary owing to variable pressures of function..

[Audio] tracings records. [image]. [image]. tracings.

[Audio] 2.INCISAL GUIDANCE: It is the effect the contact of the upper & lower anterior teeth have on the movements of the mandible. It is usually expressed in degrees of angulations from the horizontal by a line drawn in the sagittal plane between the incisal edges of the upper & lower incisor teeth when closed in centric occlusion..

[Audio] If the incisal guidance is steep, it requires steep cusps, steep occlusal plane or a steep compensating curve to affect an occlusal balance. Because of steep inclined planes, this type of occlusion is detrimental to the stability & equilibrium of the dentures base. For complete dentures, it should be as flat as esthetics & phonetics will permit.

[Audio] 3.ORIENTATION OF THE OCCLUSAL PLANE: The amount of leverage or torque (x1,x2,x3) exerted on the occlusal plane is a function of the height of the plane above the ridge. Torque = force x distance from fulcrum Boucher stated that orientation of occlusal plane becomes the third fixed factor of occlusion.

[Audio] 4.INCLINATION OF THE CUSPS: Inclination of the cusps of the teeth is the fourth factor of occlusion. It refers to the angle between the total occlusal surface of the tooth & the inclination of the cusp in relation to that surface. The cuspal inclination designated by the manufacturer is not necessarily the effective inclination when the tooth is arranged in occlusion on the articulator. The basic inclination of the cusps is made steeper when the distal end of a lower tooth is set higher than the mesial end..

[Audio] Cusps can be considered as having 2 angles: Anteroposterior. Lateral. Balanced occlusion is dependent upon the cuspal angles being parallel to the path of movements of the mandible. A restraining factor, which limits steepness of cusps, is the retention of the denture. Resultant lateral forces associated with steep cusps produce high displacing force at the fitting surface of the dentures..

[Audio] 5.PROMINENCE OF THE COMPENSATING CURVE: It is one of the most important factors in establishing a balanced occlusion. It is determined by the inclination of posterior teeth & their vertical relationship to the occlusal plane so that the occlusal surface results in a curve that is in harmony with the movement of the mandible as guided posteriorly by the condylar path..

[Audio] Monoplane balanced occlusion Non anatomic ( zero degree, non cusp, monoplane) teeth set with a compensating curve to provide some degree of protrusive and lateral balance is a widely accepted occlusal scheme. in these schemes tooth inclines are eliminated and balance is produced by antero-posterior and lateral curve and by the use of balancing ramp leading to three point balance. Interest in this scheme arose from the concern for the preservation of residual ridges and belief that elimination of tooth incline help in ridge preservation..

[Audio] CONTACTS IN BALANCED ARTICULATION Working side: The mandibular buccal cusp ridges make articular contact with the maxillary cusp ridges as the mandibular lingual cusp ridges are making contacts with the maxillary lingual cusp ridges. Balancing side: The mandibular buccal cusps & their occlusal facing ridge, contacts maxillary lingual cusps and ridge..

[Audio] Protrusion: Incisal edges of the mandibular anterior teeth contact with the lingual surface of the maxillary anterior teeth. The mesiobuccal & lingual cusp ridges of the mandibular teeth contact the distobuccal & lingual cusp ridges of the maxillary teeth..

[Audio] Advantages of balanced occlusion : 1.Stability: bilateral simultaneous contact help to seat the dentures in a stable position during mastication, swallowing & maintain retention & stability of the dentures & the health of oral tissue. As cuspal interference has been eliminated, there will be little tendency for the dentures to be dragged. 2.Balanced occlusion: In any position of occlusion, maximum number of teeth are in contact & therefore the masticatory pressure is distributed over the supporting tissues. 3.Reduced trauma: Since there will be no tilting of the dentures & the masticatory pressure will be distributed as evenly as possible, the minimum amount of damage will be done to the supporting tissue..

[Audio] 4.Functional movements: Most patients will become accustomed to dentures which have been anatomically set up far more readily than to plane line dentures because the former allow a continuation of normal masticatory movements while the latter requires an entirely new pattern of movements to be learnt. 5.Efficiency: Grinding & cutting of foodstuffs are possible because lateral & protrusive movements can be made while still maintaining balanced articulation. Due to cross arch balance, as the bolus is chewed on one side, balancing cusps will come close or will contact on the other. The dictum ‘enter bolus, exit balance’ is therefore refuted..

[Audio] 6.Dentures bases are stable even during bruxing activity. 7.Time saving: Balanced articulation having been obtained by the technician in the lab, there remains only minor spot grinding to be done & thus a considerable amount of time is saved..

[Audio] Disadvantages of balanced occlusion: 1.It is difficult to achieve in mouths where an increased vertical incisor overlap is present. 2.It may tend to encourage lateral & protrusive grinding habits. 3.A semi-adjustable or fully adjustable articulator is required..

[Audio] Summary Goal of complete denture occlusion is preservation of structure and restoration of function and esthetics Consequences of tooth loss create anatomic changes which result in differences in derivation of retention, stability and support between natural and complete denture teeth The differences in the design of natural and complete denture occlusion are the consequence of differences in the derivation of retention, stability and support.

[Audio] REFERENCES: Boucher’s Prosthodontic Treatment for Edentulous Patient”, 12th edition, Zarb-Bolender. Boucher’s Prosthodontic Treatment for Edentulous Patient”, 10th edition, Zarb-Bolender, Hickey, Carlsson. Essentials of Complete Denture Prosthodotics, 2nd Edition, Sheldon-Winkler. Complete Denture Prosthodontics – Swenson. Text Book of Complete Dentures, 5th edition, Rahn, Charles Heartwell. Complete Denture Prosthodontics – Sharry. Journal of Prosthetic Dentistry 1972; 27:246 Journal of Prosthetic Dentistry 1978; 39 : 484. Journal of Prosthetic Dentistry 1977; 38:601. Journal of Prosthetic Dentistry 1972; 25:94-100. Journal of Prosthetic Dentistry 2001; 85(1):15-19. Journal of Prosthetic Dentistry 1971; 25(2):121-138. Journal of Prosthetic Dentistry.

[Audio] Thank You…. Thank You….